The effect of extracellular Hsp90β and TGF-β1 on colon cancer biology
- Authors: Perks, Tamarin
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/55896 , vital:26753
- Description: The TGF-β signaling pathway is known to be one of the most commonly mutated pathways in human cancers, while Hsp90 is a bone fide drug target that is involved in regulating the conformation and activity of many oncoproteins. The role of intracellular Hsp90 in cancer has thus far been established and there is a growing link between extracellular Hsp90 and cancer metastasis, as well as the role of TGF-β in metastasis. This study aimed to analyse the interaction between Hsp90 (both intracellular and extracellular) and the TGF-β machinery in cancer cells, as well as to determine the effect of these proteins on cellular responses on the biology of cancer cells. This was achieved by studying the expression of Hsp90; TGF-βRII and TGF-β1 in cancer cell lines of various origins using flow cytometry, ELISA, and western blot analysis. The genetically paired SW480 and SW620 colon cancer cell lines, derived from a primary tumour and lymph node metastasis, respectively, were selected for further study due to differences in expression levels and activation of the TGF-β1 pathway. SW480 cells expressed double the level of TGF-βRII compared to SW620 cells, while SW620 expressed two times more extracellular TGF-β1 than SW480 cells. A direct interaction between TGF-β1 and Hsp90β was determined in vitro, and confirmed in vivo in SW620 cells. Growth, adhesion and migration were analysed in SW480 and SW620 cells. SW480 cells adhered significantly faster than SW620 cells, while SW620 cells had a greater rate of migration. Inhibiting the TGF-β pathway, specifically TGF-βRI, using SB 431542, as well as inhibiting Hsp90 with novobiocin, caused an increase in migration in SW480 cells. Only the addition of TGF-β1 in combination with Hsp90 as well as SB 431542 caused an increase in migration in SW620 cells. The canonical TGF-β1/TGF-βRI/TGF-βRII pathway may be constitutively active in SW620 cells and the inhibition of TGF-βRI may suggest an alternate pathway or receptor in both SW480 and SW620 cells.
- Full Text:
- Date Issued: 2015
- Authors: Perks, Tamarin
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/55896 , vital:26753
- Description: The TGF-β signaling pathway is known to be one of the most commonly mutated pathways in human cancers, while Hsp90 is a bone fide drug target that is involved in regulating the conformation and activity of many oncoproteins. The role of intracellular Hsp90 in cancer has thus far been established and there is a growing link between extracellular Hsp90 and cancer metastasis, as well as the role of TGF-β in metastasis. This study aimed to analyse the interaction between Hsp90 (both intracellular and extracellular) and the TGF-β machinery in cancer cells, as well as to determine the effect of these proteins on cellular responses on the biology of cancer cells. This was achieved by studying the expression of Hsp90; TGF-βRII and TGF-β1 in cancer cell lines of various origins using flow cytometry, ELISA, and western blot analysis. The genetically paired SW480 and SW620 colon cancer cell lines, derived from a primary tumour and lymph node metastasis, respectively, were selected for further study due to differences in expression levels and activation of the TGF-β1 pathway. SW480 cells expressed double the level of TGF-βRII compared to SW620 cells, while SW620 expressed two times more extracellular TGF-β1 than SW480 cells. A direct interaction between TGF-β1 and Hsp90β was determined in vitro, and confirmed in vivo in SW620 cells. Growth, adhesion and migration were analysed in SW480 and SW620 cells. SW480 cells adhered significantly faster than SW620 cells, while SW620 cells had a greater rate of migration. Inhibiting the TGF-β pathway, specifically TGF-βRI, using SB 431542, as well as inhibiting Hsp90 with novobiocin, caused an increase in migration in SW480 cells. Only the addition of TGF-β1 in combination with Hsp90 as well as SB 431542 caused an increase in migration in SW620 cells. The canonical TGF-β1/TGF-βRI/TGF-βRII pathway may be constitutively active in SW620 cells and the inhibition of TGF-βRI may suggest an alternate pathway or receptor in both SW480 and SW620 cells.
- Full Text:
- Date Issued: 2015
A study of South African computer users' password usage habits and attitude towards password security
- Authors: Friendman, Brandon
- Date: 2014
- Subjects: Computers -- Access control -- Passwords , Computer users -- Attitudes , Internet -- Access control , Internet -- Security measures , Internet -- Management , Data protection
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:4700
- Description: The challenge of having to create and remember a secure password for each user account has become a problem for many computer users and can lead to bad password management practices. Simpler and less secure passwords are often selected and are regularly reused across multiple user accounts. Computer users within corporations and institutions are subject to password policies, policies which require users to create passwords of a specified length and composition and change passwords regularly. These policies often prevent users from reusing previous selected passwords. Security vendors and professionals have sought to improve or even replace password authentication. Technologies such as multi-factor authentication and single sign-on have been developed to complement or even replace password authentication. The objective of the study was to investigate the password habits of South African computer and internet users. The aim was to assess their attitudes toward password security, to determine whether password policies a↵ect the manner in which they manage their passwords and to investigate their exposure to alternate authentication technologies. The results from the online survey demonstrated that password practices of the participants across their professional and personal contexts were generally insecure. Participants often used shorter, simpler and ultimately less secure passwords. Participants would try to memorise all of their passwords or reuse the same password on most of their accounts. Many participants had not received any security awareness training, and additional security technologies (such as multi-factor authentication or password managers) were seldom used or provided to them. The password policies encountered by the participants in their organisations did little towards encouraging the users to apply more secure password practices. Users lack the knowledge and understanding about password security as they had received little or no training pertaining to it.
- Full Text:
- Date Issued: 2014
- Authors: Friendman, Brandon
- Date: 2014
- Subjects: Computers -- Access control -- Passwords , Computer users -- Attitudes , Internet -- Access control , Internet -- Security measures , Internet -- Management , Data protection
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:4700
- Description: The challenge of having to create and remember a secure password for each user account has become a problem for many computer users and can lead to bad password management practices. Simpler and less secure passwords are often selected and are regularly reused across multiple user accounts. Computer users within corporations and institutions are subject to password policies, policies which require users to create passwords of a specified length and composition and change passwords regularly. These policies often prevent users from reusing previous selected passwords. Security vendors and professionals have sought to improve or even replace password authentication. Technologies such as multi-factor authentication and single sign-on have been developed to complement or even replace password authentication. The objective of the study was to investigate the password habits of South African computer and internet users. The aim was to assess their attitudes toward password security, to determine whether password policies a↵ect the manner in which they manage their passwords and to investigate their exposure to alternate authentication technologies. The results from the online survey demonstrated that password practices of the participants across their professional and personal contexts were generally insecure. Participants often used shorter, simpler and ultimately less secure passwords. Participants would try to memorise all of their passwords or reuse the same password on most of their accounts. Many participants had not received any security awareness training, and additional security technologies (such as multi-factor authentication or password managers) were seldom used or provided to them. The password policies encountered by the participants in their organisations did little towards encouraging the users to apply more secure password practices. Users lack the knowledge and understanding about password security as they had received little or no training pertaining to it.
- Full Text:
- Date Issued: 2014
An electrospun nanofiber colorimetric probe for detection of Alkaline Phosphatase for diagnosis of liver toxicity
- Authors: Mohale, Mamello
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54532 , vital:26581
- Description: A novel electrospun nanofiber colorimetric probe for the detection of Alkaline Phosphatase (ALP) for diagnosis of liver toxicity was developed through electrospinning of a para nitrophenyl phosphate (pNPP) functionalised nylon polymer. The chemical stability of the enzyme substrate (pNPP) and its two products (para nitrophenol (pNP) and para nitrophenolate (pNPL)) was evaluated in biological (pH 7.4), acidic (pH 2) and alkaline (pH 9) pH, respectively. Enzyme kinetics models of Michaelis Menten (MM) and Lineweaver Burk (LB) were used to characterise free ALP. Solution and nanofiber assaying of free ALP and 10x diluted serum (spiked with ALP) was also carried out. The results demonstrated that pNPP and pNP were colourless while pNPL was yellow which indicated that all reagents were chemically stable. In addition, the chromophore of pNPL exhibited a strong molar extinction coefficient (ε) of 18,458 M-1 cm-1. LB plot being the most accurate compared to MM showed Vmax, Km and excess substrate concentration of 5.5 × 10-3 μmol/min-1, 0.025 mM and 0.25 mM respectively. Solution and nanofiber assaying of free ALP and serum confirmed a direct proportional correlation between the pNPL yellow colour intensity and enzyme activity up to 858 IU/L and 820 IU/L respectively. The dipping of the nanofiber layer into solution showed that the leaching rate of pNPP was extremely high at 1.37 × 10-3 A/min-1 as was observed after only the first 0.25 min interval. However, this was not of great concern since it was also observed that administration of the sample (20 μL) by a dropwise method minimised leaching compared to dipping. The preliminary findings on the effect of temperature on the chemical stability of pNPP indicated that it was stable below temperatures of 40°C while it hydrolysed at 80°C. Therefore a sensitive, rapid and simple colorimetric probe for the detection of ALP was developed. The probe exhibited characteristics that make it suitable to be incorporated into point of care colorimetric liver toxicity diagnostic devices for applications in resource poor settings and telemedicine.
- Full Text:
- Date Issued: 2014
- Authors: Mohale, Mamello
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54532 , vital:26581
- Description: A novel electrospun nanofiber colorimetric probe for the detection of Alkaline Phosphatase (ALP) for diagnosis of liver toxicity was developed through electrospinning of a para nitrophenyl phosphate (pNPP) functionalised nylon polymer. The chemical stability of the enzyme substrate (pNPP) and its two products (para nitrophenol (pNP) and para nitrophenolate (pNPL)) was evaluated in biological (pH 7.4), acidic (pH 2) and alkaline (pH 9) pH, respectively. Enzyme kinetics models of Michaelis Menten (MM) and Lineweaver Burk (LB) were used to characterise free ALP. Solution and nanofiber assaying of free ALP and 10x diluted serum (spiked with ALP) was also carried out. The results demonstrated that pNPP and pNP were colourless while pNPL was yellow which indicated that all reagents were chemically stable. In addition, the chromophore of pNPL exhibited a strong molar extinction coefficient (ε) of 18,458 M-1 cm-1. LB plot being the most accurate compared to MM showed Vmax, Km and excess substrate concentration of 5.5 × 10-3 μmol/min-1, 0.025 mM and 0.25 mM respectively. Solution and nanofiber assaying of free ALP and serum confirmed a direct proportional correlation between the pNPL yellow colour intensity and enzyme activity up to 858 IU/L and 820 IU/L respectively. The dipping of the nanofiber layer into solution showed that the leaching rate of pNPP was extremely high at 1.37 × 10-3 A/min-1 as was observed after only the first 0.25 min interval. However, this was not of great concern since it was also observed that administration of the sample (20 μL) by a dropwise method minimised leaching compared to dipping. The preliminary findings on the effect of temperature on the chemical stability of pNPP indicated that it was stable below temperatures of 40°C while it hydrolysed at 80°C. Therefore a sensitive, rapid and simple colorimetric probe for the detection of ALP was developed. The probe exhibited characteristics that make it suitable to be incorporated into point of care colorimetric liver toxicity diagnostic devices for applications in resource poor settings and telemedicine.
- Full Text:
- Date Issued: 2014
An investigation of the role of mitochondrial STAT3 and modulation of Reactive Oxygen Species in adipocyte differentiation
- Authors: Kramer, Adam Hildyard
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54632 , vital:26595
- Description: Stem cells have the ability to differentiate into a myriad of different cell types. The understanding of the differentiation process is of paramount importance if we are to use these cells in the lab as well as in therapeutics. Here, the levels and localization of the signal transducer and activator of transcription 3 (STAT3), with particular attention focused on the mitochondrial serine 727 phosphorylated form of STAT3 (pSTAT3S727) during differentiation, was investigated. Using the murine preadipocyte progenitor cell line 3T3-L1, as well as adipose derived human mesenchymal stem cells (HMSC-ad) as differentiation models, the relative levels of Reactive Oxygen Species (ROS) and the levels and localization of STAT3 were investigated during the differentiation process. ROS is known to play an important signalling role during differentiation and is well reported during the events of adipogenesis. ROS are generated as a by-product in the Electron Transport Chain (ETC), and it has recently been reported that pSTAT3S727 plays an important role at complex I of the ETC. Various techniques including fluorescence confocal microscopy, flow cytometry and Western blots were utilized to investigate the non-canonical role STAT3 plays during adipogenesis. Mitochondrial isolations were performed to investigate the levels of STAT3 in the mitochondria during differentiation. Further to this, an impedance based real time differentiation assay was developed using the xCELLigence Real Time Cell Analyser to monitor differentiation and the affects various compounds, including a STAT3 inhibitor, have on differentiation. Results indicate that upon induction of differentiation, levels of mitochondrial pSTAT3S727 dramatically decrease and leave the mitochondria. This corresponds to increasing levels of ROS. The canonical active form of STAT3 following phosphorylation on tyrosine 705 (pSTAT3Y705) was found to decrease and lose its nuclear localization. These initial results indicate that STAT3 plays an important non-canonical role in the mitochondria during differentiation.
- Full Text:
- Date Issued: 2014
- Authors: Kramer, Adam Hildyard
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54632 , vital:26595
- Description: Stem cells have the ability to differentiate into a myriad of different cell types. The understanding of the differentiation process is of paramount importance if we are to use these cells in the lab as well as in therapeutics. Here, the levels and localization of the signal transducer and activator of transcription 3 (STAT3), with particular attention focused on the mitochondrial serine 727 phosphorylated form of STAT3 (pSTAT3S727) during differentiation, was investigated. Using the murine preadipocyte progenitor cell line 3T3-L1, as well as adipose derived human mesenchymal stem cells (HMSC-ad) as differentiation models, the relative levels of Reactive Oxygen Species (ROS) and the levels and localization of STAT3 were investigated during the differentiation process. ROS is known to play an important signalling role during differentiation and is well reported during the events of adipogenesis. ROS are generated as a by-product in the Electron Transport Chain (ETC), and it has recently been reported that pSTAT3S727 plays an important role at complex I of the ETC. Various techniques including fluorescence confocal microscopy, flow cytometry and Western blots were utilized to investigate the non-canonical role STAT3 plays during adipogenesis. Mitochondrial isolations were performed to investigate the levels of STAT3 in the mitochondria during differentiation. Further to this, an impedance based real time differentiation assay was developed using the xCELLigence Real Time Cell Analyser to monitor differentiation and the affects various compounds, including a STAT3 inhibitor, have on differentiation. Results indicate that upon induction of differentiation, levels of mitochondrial pSTAT3S727 dramatically decrease and leave the mitochondria. This corresponds to increasing levels of ROS. The canonical active form of STAT3 following phosphorylation on tyrosine 705 (pSTAT3Y705) was found to decrease and lose its nuclear localization. These initial results indicate that STAT3 plays an important non-canonical role in the mitochondria during differentiation.
- Full Text:
- Date Issued: 2014
Assessing the genetic diversity of catface rockcod epinephelus andersoni in the subtropical Western Indian Ocean and modelling the effects of climate change on their distribution
- Authors: Coppinger, Christine Rose
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54499 , vital:26570
- Description: The catface rockcod Epinephelus andersoni is a range-restricted species that is endemic to the southeast coast of Africa from Quissico in Mozambique (subtropical) to Knysna in South Africa (warmtemperate). Its complex life-history, long-lived nature and high residency make E. andersoni potentially vulnerable to over-exploitation. Epinephelus andersoni is an important fishery species and has shown signs of depletion. Due to inadequate information necessary for management and conservation, further research is vital, particularly in the face of potentially significant climatic changes which could put further pressure on E. andersoni. The aim of the study was to provide information for the management of E. andersoni, with considerations for the possibly detrimental effects of future climate change. The objectives of this study were to describe the genetic structure and diversity of E. andersoni and to determine possible range shifts of E. andersoni with future changes in sea surface temperature. Genetic samples were collected throughout the distribution of E. andersoni. Standard DNA extraction and PCR using universal primers were conducted and nuclear (RPS7-1) and mitochondrial (cytochrome b) data were analysed to determine genetic diversity. A combination of nuclear and mitochondrial markers was used to ensure that the results were robust. RPS7-1 haplotype diversity was high (0.801) and an AMOVA on the RPS7-1 data showed significantly high among group variation (ΦCT = 0.204, p < 0.05) between five groups: 1. Quissico to Inhaca; 2. Cape Vidal to Port Edward; 3 Port St Johns to Coffee Bay; 4. Mbashe; 5. Port Alfred. This geographic structuring could be attributed to low gene flow across barriers such as the Port Alfred upwelling cell, the Mozambique Channel eddies and smaller more localised upwelling cells such as the Port St Johns cell. The cytochrome b results contrastingly indicate low haplotype diversity (0.309) and no differentiation (ΦCT = 0.265, p = 0.074) between groups and support the hypothesis of a historical population bottleneck. This may be due to an unusually slower mutation rate of the cytochrome b region than the RPS7-1 region, resulting in the RPS7-1 data showing a more recent picture of diversification. To complement the genetic results, niche modelling techniques were used to determine range shifts of E. andersoni with future temperature trends using species distribution and climatic data. The model illustrated a contraction of the E. andersoni distribution as well as future intensification of various upwelling cells along the south-east African coast including the Port Alfred upwelling cell. Due to the low gene flow across these barriers this intensification could decrease the resilience of E. andersoni, as its range becomes more limited with global change. The genetic data and modelling results combined provide useful information on which to base future fisheries management.
- Full Text:
- Date Issued: 2014
- Authors: Coppinger, Christine Rose
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54499 , vital:26570
- Description: The catface rockcod Epinephelus andersoni is a range-restricted species that is endemic to the southeast coast of Africa from Quissico in Mozambique (subtropical) to Knysna in South Africa (warmtemperate). Its complex life-history, long-lived nature and high residency make E. andersoni potentially vulnerable to over-exploitation. Epinephelus andersoni is an important fishery species and has shown signs of depletion. Due to inadequate information necessary for management and conservation, further research is vital, particularly in the face of potentially significant climatic changes which could put further pressure on E. andersoni. The aim of the study was to provide information for the management of E. andersoni, with considerations for the possibly detrimental effects of future climate change. The objectives of this study were to describe the genetic structure and diversity of E. andersoni and to determine possible range shifts of E. andersoni with future changes in sea surface temperature. Genetic samples were collected throughout the distribution of E. andersoni. Standard DNA extraction and PCR using universal primers were conducted and nuclear (RPS7-1) and mitochondrial (cytochrome b) data were analysed to determine genetic diversity. A combination of nuclear and mitochondrial markers was used to ensure that the results were robust. RPS7-1 haplotype diversity was high (0.801) and an AMOVA on the RPS7-1 data showed significantly high among group variation (ΦCT = 0.204, p < 0.05) between five groups: 1. Quissico to Inhaca; 2. Cape Vidal to Port Edward; 3 Port St Johns to Coffee Bay; 4. Mbashe; 5. Port Alfred. This geographic structuring could be attributed to low gene flow across barriers such as the Port Alfred upwelling cell, the Mozambique Channel eddies and smaller more localised upwelling cells such as the Port St Johns cell. The cytochrome b results contrastingly indicate low haplotype diversity (0.309) and no differentiation (ΦCT = 0.265, p = 0.074) between groups and support the hypothesis of a historical population bottleneck. This may be due to an unusually slower mutation rate of the cytochrome b region than the RPS7-1 region, resulting in the RPS7-1 data showing a more recent picture of diversification. To complement the genetic results, niche modelling techniques were used to determine range shifts of E. andersoni with future temperature trends using species distribution and climatic data. The model illustrated a contraction of the E. andersoni distribution as well as future intensification of various upwelling cells along the south-east African coast including the Port Alfred upwelling cell. Due to the low gene flow across these barriers this intensification could decrease the resilience of E. andersoni, as its range becomes more limited with global change. The genetic data and modelling results combined provide useful information on which to base future fisheries management.
- Full Text:
- Date Issued: 2014
Bacterial degradation of waste coal
- Authors: Madikiza, Lwazikazi
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54576 , vital:26590
- Description: As an energy source coal has one of the largest agglomerations in the world. Consequently mining of coal creates large volumes of waste in the form of low ranks coals. The complex structure of coal makes it difficult for the microorganisms to degrade and relatively few bacteria and fungi have been shown to break down coal. This study aimed to investigate bacteria not previously known to degrade coal. In this study bacteria were isolated from hydrocarbon contaminated sites and inoculated in coal medium where coal served as the only carbon source. Three strains produced a yellow – brown supernatant after 14 d of incubation at 30 °C. Bacteria generating a yellow – brown coloured supernatant were presumed to possess coal degrading capabilities and the best performing of these bacterial species was identified using 16s rDNA as Bacillus flexus. Scanning electron microscopy showed that there was a close association between the bacterium and substrate coal. The close association of bacteria to substrate suggested that these organisms were able to maximize solubilisation. FT-IR spectroscopic analysis demonstrated the addition of single bonded compounds COOH, OH, CN and CH that were absent prior to bacterial interaction. The increase in oxygen rich regions indicated degradation of the coal substrate. Elemental analysis showed that there was a decrease in carbon content from 47 % to 24 % during the 14 day incubation period. Reduction in coal carbon content was assumed to be due to bacterial utilization for metabolism and growth particularly as untreated coal substrate showed minimal loss of carbon. Analysis of the residual culture medium revealed that there was a linear increase in humic-like substance concentration for 8 d, coincident with increased coal biosolubilisation and colour change. Laccase activity was insignificant, and at 13 d enzyme activity was only 5×10-3 U/L suggesting that B. flexus may use a different mechanism to degrade coal. Residual culture medium remaining after bacterial action on the coal substrate appeared to possess plant growth promoting activity. This soluble biodegradation product with characteristics similar to humic acid-like substances was shown to impact growth of radish cotyledons. Expansion of isolated radish cotyledons was enhanced by 140% when incubated in coal biodegradation product. In conclusion, this study has yielded B. flexus and two other unidentified bacteria, isolated from polyaromatic hydrocarbon contaminated soils, and demonstrated the ability of these microorganisms to degrade waste coal. Further studies to elucidate the mechanism of coal breakdown by B. flexus, synergies with other coal degrading microorganisms, and incorporation of bacterium into Fungcoal bioprocess technology is imminent.
- Full Text:
- Date Issued: 2014
- Authors: Madikiza, Lwazikazi
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54576 , vital:26590
- Description: As an energy source coal has one of the largest agglomerations in the world. Consequently mining of coal creates large volumes of waste in the form of low ranks coals. The complex structure of coal makes it difficult for the microorganisms to degrade and relatively few bacteria and fungi have been shown to break down coal. This study aimed to investigate bacteria not previously known to degrade coal. In this study bacteria were isolated from hydrocarbon contaminated sites and inoculated in coal medium where coal served as the only carbon source. Three strains produced a yellow – brown supernatant after 14 d of incubation at 30 °C. Bacteria generating a yellow – brown coloured supernatant were presumed to possess coal degrading capabilities and the best performing of these bacterial species was identified using 16s rDNA as Bacillus flexus. Scanning electron microscopy showed that there was a close association between the bacterium and substrate coal. The close association of bacteria to substrate suggested that these organisms were able to maximize solubilisation. FT-IR spectroscopic analysis demonstrated the addition of single bonded compounds COOH, OH, CN and CH that were absent prior to bacterial interaction. The increase in oxygen rich regions indicated degradation of the coal substrate. Elemental analysis showed that there was a decrease in carbon content from 47 % to 24 % during the 14 day incubation period. Reduction in coal carbon content was assumed to be due to bacterial utilization for metabolism and growth particularly as untreated coal substrate showed minimal loss of carbon. Analysis of the residual culture medium revealed that there was a linear increase in humic-like substance concentration for 8 d, coincident with increased coal biosolubilisation and colour change. Laccase activity was insignificant, and at 13 d enzyme activity was only 5×10-3 U/L suggesting that B. flexus may use a different mechanism to degrade coal. Residual culture medium remaining after bacterial action on the coal substrate appeared to possess plant growth promoting activity. This soluble biodegradation product with characteristics similar to humic acid-like substances was shown to impact growth of radish cotyledons. Expansion of isolated radish cotyledons was enhanced by 140% when incubated in coal biodegradation product. In conclusion, this study has yielded B. flexus and two other unidentified bacteria, isolated from polyaromatic hydrocarbon contaminated soils, and demonstrated the ability of these microorganisms to degrade waste coal. Further studies to elucidate the mechanism of coal breakdown by B. flexus, synergies with other coal degrading microorganisms, and incorporation of bacterium into Fungcoal bioprocess technology is imminent.
- Full Text:
- Date Issued: 2014
Characterization and application of phthalocyanine-magnetic nanoparticle conjugates anchored to electrospun polyamide nanofibers
- Authors: Ledwaba, Mpho
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54610 , vital:26593
- Description: This work presents the syntheses, photophysical and photochemical characterization of zinc tetracarboxyphenoxy phthalocyanine (ZnTCPPc, 3) and its gadolinium oxide nanoparticle conjugate (4). By means of spectroscopic and microscopic characterization, the conjugation of the ZnTCPPc to the silica coated gadolinium oxide nanoparticles (Si-Gd2O3 NPs, 2) through an amide bond was confirmed. The thermal stability, morphology, nanoparticle sizes and their conjugates with the Pc were studied using ThermoGravimetric Analysis (TGA), Fourier Transform Infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and powder X-ray diffractometry (XRD). Conjugation of ZnTCPPc to the magnetic nanoparticles, proved to have a negligible effect on the photophysical parameters of the phthalocyanine, where a slight decrease in fluorescence and triplet quantum yields and lifetimes was observed. The singlet oxygen quantum yield, however, increased slightly upon conjugation, suggesting that the overall efficiency of the ZnTCPPc as a photosensitizer had improved. Physical mixing of the ZnTCPPc and the silica-coated gadolinium nanoparticles also showed an improvement in the singlet oxygen quantum yield and triplet lifetime, also showing an enhanced efficiency for the photosensitizer and therefore photocatalysis. ZnTCPPc (3) alone and the Pc-gadolinium oxide nanoparticle conjugate (4) were therefore electrospun into nanofibers to create a solid support. The fibers were characterized and their diameter sizes and composition was studied confirming the incorporation of the phthalocyanine and gadolinium oxide nanoparticle. Increased singlet oxygen generation resulted in increased Photodegradation of the environmental pollutant Orange G and the fibers were found to be more efficient as photocatalysts compared to the photosensitizer in solution. The nanomaterial may therefore be applied to the photodegradation of Orange G.
- Full Text:
- Date Issued: 2014
- Authors: Ledwaba, Mpho
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54610 , vital:26593
- Description: This work presents the syntheses, photophysical and photochemical characterization of zinc tetracarboxyphenoxy phthalocyanine (ZnTCPPc, 3) and its gadolinium oxide nanoparticle conjugate (4). By means of spectroscopic and microscopic characterization, the conjugation of the ZnTCPPc to the silica coated gadolinium oxide nanoparticles (Si-Gd2O3 NPs, 2) through an amide bond was confirmed. The thermal stability, morphology, nanoparticle sizes and their conjugates with the Pc were studied using ThermoGravimetric Analysis (TGA), Fourier Transform Infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and powder X-ray diffractometry (XRD). Conjugation of ZnTCPPc to the magnetic nanoparticles, proved to have a negligible effect on the photophysical parameters of the phthalocyanine, where a slight decrease in fluorescence and triplet quantum yields and lifetimes was observed. The singlet oxygen quantum yield, however, increased slightly upon conjugation, suggesting that the overall efficiency of the ZnTCPPc as a photosensitizer had improved. Physical mixing of the ZnTCPPc and the silica-coated gadolinium nanoparticles also showed an improvement in the singlet oxygen quantum yield and triplet lifetime, also showing an enhanced efficiency for the photosensitizer and therefore photocatalysis. ZnTCPPc (3) alone and the Pc-gadolinium oxide nanoparticle conjugate (4) were therefore electrospun into nanofibers to create a solid support. The fibers were characterized and their diameter sizes and composition was studied confirming the incorporation of the phthalocyanine and gadolinium oxide nanoparticle. Increased singlet oxygen generation resulted in increased Photodegradation of the environmental pollutant Orange G and the fibers were found to be more efficient as photocatalysts compared to the photosensitizer in solution. The nanomaterial may therefore be applied to the photodegradation of Orange G.
- Full Text:
- Date Issued: 2014
Gold mineralization in a high grade metamorphic terrane in the Handeni District, Eastern Tanzania
- Bitesigirwe, Godfrey Stephen
- Authors: Bitesigirwe, Godfrey Stephen
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54756 , vital:26609
- Description: Most orogenic type gold deposits are formed under low greenschist facies to mid amphibolite facies metamorphic conditions and deposition is either structurally or lithologically controlled. A few known gold deposits found in high grade metamorphic terranes include those in the Yilgarn craton in Australia, Renco in Zimbabwe, Hemlo in Canada and the recently discovered Handeni deposit in Tanzania. Within Tanzania, gold deposits are mainly hosted in Archaean low grade metamorphic rocks commonly known as the Lake Victoria greenstone belt. The greenstone belts of Tanzania are of Nyanzian age (> 2.5Ga) and are located to the south and east of Lake Victoria on the Tanzania craton. The Tanzania Craton is surrounded by Usagaran 1.9 Ga rocks (the east African orogenic belt (EAO) better known as the Mozambique belt) to the east and the Ubendian belt to the south and west. Published reports show that the eastern part of the Tanzania Craton is dominated by the fragments of Archaean rocks. Metamorphism along East Africa and the Tanzania Craton is due to several geological events. These geological events include the intrusion of granites in the Archaean Tanzania Craton (3 Ga), subduction of ocean plate resulted to the formation of Usagaran belt (1.9 Ga), opening and closure of Mozambique Ocean, which resulted in the formation of the Mozambique belt between 700 – 800 Ma and the Pan African orogeny at 640 – 620 Ma, which is associated with the formation of Gondwana. It is believed that fragments from the Archaean Tanzania craton were re - metamorphosed during these events. The Handeni project (the focus of this thesis) is located in the northern portion of the eastern part of the Usagaran belt (1.9 Ga) comprising the eastern part of Archaean Tanzania Craton. The area is characterized by Proterozic rocks of basaltic composition. The documented 2.7 Ga rocks at the Kilindi Handeni Superterrane at the northern part of the Usagaran belt correlate well with 2.7 Ga of Nyanzian rocks of Archaean Tanzania craton. The Handeni project area is geologically dominated by metamorphosed and deformed units of quartzofeldspathic gneisses, migmatitic gneiss, garnet silicified rock, garnetiferous amphibolite, garnetiferous granulite, graphitic schist and hornblende pyroxenite. Intensive deformation features that were developed include folds (sheath folds, micro and macro scales), faults, shears and regional thrusts. This thesis focuses on identifying the protolith of the rocks, alteration minerals, and metamorphic assemblages in the project area in order to understand the timing of gold mineralization. Geological investigation of core, ore petrology and mineralogy, mineral composition by using JEOL microprobe analysis and XRF analysis of bulk rocks were utilized. All the analytical work was done at the Geology laboratory, Rhodes University. Petrographic analysis shows that the rocks sampled in the study area are characterized by alteration minerals such as calcite, dolomite and sericite. Sulphide minerals including chalcopyrite, pyrrhotite, pyrite, pentlandite and gersdorffite were identified. Gold mineralization is associated with disseminated sulphides in association with trace amounts of base metals. Four rock types were proposed as host rocks for the mineralization, namely garnet silicified rock with superimposed quartz veins, garnetiferous amphibolite, garnetiferous granulite and hornblende pyroxenite. Fold troughs, filled fractures associated with episodes of folding, quartz veins and shear zones are suggested as gold precipitation sites. The presence of high grade metamorphic rocks containing gold, intermediate to low grade assemblages with sulphides and associated hydrothermal alteration as well as a complex deformation history suggests that the Handeni mineralization took place over an extended time period stretching from a ductile to a brittle environment.
- Full Text:
- Date Issued: 2014
- Authors: Bitesigirwe, Godfrey Stephen
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54756 , vital:26609
- Description: Most orogenic type gold deposits are formed under low greenschist facies to mid amphibolite facies metamorphic conditions and deposition is either structurally or lithologically controlled. A few known gold deposits found in high grade metamorphic terranes include those in the Yilgarn craton in Australia, Renco in Zimbabwe, Hemlo in Canada and the recently discovered Handeni deposit in Tanzania. Within Tanzania, gold deposits are mainly hosted in Archaean low grade metamorphic rocks commonly known as the Lake Victoria greenstone belt. The greenstone belts of Tanzania are of Nyanzian age (> 2.5Ga) and are located to the south and east of Lake Victoria on the Tanzania craton. The Tanzania Craton is surrounded by Usagaran 1.9 Ga rocks (the east African orogenic belt (EAO) better known as the Mozambique belt) to the east and the Ubendian belt to the south and west. Published reports show that the eastern part of the Tanzania Craton is dominated by the fragments of Archaean rocks. Metamorphism along East Africa and the Tanzania Craton is due to several geological events. These geological events include the intrusion of granites in the Archaean Tanzania Craton (3 Ga), subduction of ocean plate resulted to the formation of Usagaran belt (1.9 Ga), opening and closure of Mozambique Ocean, which resulted in the formation of the Mozambique belt between 700 – 800 Ma and the Pan African orogeny at 640 – 620 Ma, which is associated with the formation of Gondwana. It is believed that fragments from the Archaean Tanzania craton were re - metamorphosed during these events. The Handeni project (the focus of this thesis) is located in the northern portion of the eastern part of the Usagaran belt (1.9 Ga) comprising the eastern part of Archaean Tanzania Craton. The area is characterized by Proterozic rocks of basaltic composition. The documented 2.7 Ga rocks at the Kilindi Handeni Superterrane at the northern part of the Usagaran belt correlate well with 2.7 Ga of Nyanzian rocks of Archaean Tanzania craton. The Handeni project area is geologically dominated by metamorphosed and deformed units of quartzofeldspathic gneisses, migmatitic gneiss, garnet silicified rock, garnetiferous amphibolite, garnetiferous granulite, graphitic schist and hornblende pyroxenite. Intensive deformation features that were developed include folds (sheath folds, micro and macro scales), faults, shears and regional thrusts. This thesis focuses on identifying the protolith of the rocks, alteration minerals, and metamorphic assemblages in the project area in order to understand the timing of gold mineralization. Geological investigation of core, ore petrology and mineralogy, mineral composition by using JEOL microprobe analysis and XRF analysis of bulk rocks were utilized. All the analytical work was done at the Geology laboratory, Rhodes University. Petrographic analysis shows that the rocks sampled in the study area are characterized by alteration minerals such as calcite, dolomite and sericite. Sulphide minerals including chalcopyrite, pyrrhotite, pyrite, pentlandite and gersdorffite were identified. Gold mineralization is associated with disseminated sulphides in association with trace amounts of base metals. Four rock types were proposed as host rocks for the mineralization, namely garnet silicified rock with superimposed quartz veins, garnetiferous amphibolite, garnetiferous granulite and hornblende pyroxenite. Fold troughs, filled fractures associated with episodes of folding, quartz veins and shear zones are suggested as gold precipitation sites. The presence of high grade metamorphic rocks containing gold, intermediate to low grade assemblages with sulphides and associated hydrothermal alteration as well as a complex deformation history suggests that the Handeni mineralization took place over an extended time period stretching from a ductile to a brittle environment.
- Full Text:
- Date Issued: 2014
Invariant optimal control on the three-dimensional semi-Euclidean group: control affine and quadratic Hamilton-Poisson systems
- Authors: Barrett, Dennis Ian
- Date: 2014
- Subjects: Automorphisms , Symmetry (Mathematics) , Lyapunov stability , Geometry, Riemannian , Geometry, Affine , Elliptic functions
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64805 , vital:28605
- Description: In this thesis we consider invariant control systems and Hamilton-Poisson systems on the three dimensional semi-Euclidean group SE(1,1). We first classify the left-invariant control affine systems (under detached feedback equivalence). We provide a complete list of normal forms, as well as classifying conditions. As a corollary to this classification, we derive controllability criteria for control affine systems on SE(1,1). Secondly, we consider quadratic Hamilton-Poisson systems on the (minus) Lie-Poisson space se(1,1)*. These systems are classified up to an affine isomorphism. Six normal forms are identified for the homogeneous case, whereas sixteen representatives (including several infinite families) are obtained for the inhomogeneous systems. Thereafter we consider the stability and integration of the normal forms obtained. For all homogeneous systems, and a subclass of inhomogeneous systems, we perform a complete stability analysis and derive explicit expressions for all integral curves. (The extremal controls of a large class of optimal control problems on SE(1,1) are linearly related to these integral curves.) Lastly, we discuss the Riemannian and sub-Riemannian problems. The (left-invariant) Riemannian and sub-Riemannian structures on SE(1,1) are classified, up to isometric group automorphisms and scaling. Explicit expressions for the geodesics of the normalised structures are found.
- Full Text:
- Date Issued: 2014
- Authors: Barrett, Dennis Ian
- Date: 2014
- Subjects: Automorphisms , Symmetry (Mathematics) , Lyapunov stability , Geometry, Riemannian , Geometry, Affine , Elliptic functions
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64805 , vital:28605
- Description: In this thesis we consider invariant control systems and Hamilton-Poisson systems on the three dimensional semi-Euclidean group SE(1,1). We first classify the left-invariant control affine systems (under detached feedback equivalence). We provide a complete list of normal forms, as well as classifying conditions. As a corollary to this classification, we derive controllability criteria for control affine systems on SE(1,1). Secondly, we consider quadratic Hamilton-Poisson systems on the (minus) Lie-Poisson space se(1,1)*. These systems are classified up to an affine isomorphism. Six normal forms are identified for the homogeneous case, whereas sixteen representatives (including several infinite families) are obtained for the inhomogeneous systems. Thereafter we consider the stability and integration of the normal forms obtained. For all homogeneous systems, and a subclass of inhomogeneous systems, we perform a complete stability analysis and derive explicit expressions for all integral curves. (The extremal controls of a large class of optimal control problems on SE(1,1) are linearly related to these integral curves.) Lastly, we discuss the Riemannian and sub-Riemannian problems. The (left-invariant) Riemannian and sub-Riemannian structures on SE(1,1) are classified, up to isometric group automorphisms and scaling. Explicit expressions for the geodesics of the normalised structures are found.
- Full Text:
- Date Issued: 2014
Modelling the spatial and genetic response of the endemic sparid: Polysteganus praeorbitalis (Pisces: Sparidae) to climate change in the Agulhas Current system
- Authors: Isemonger, Devin Neil
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54509 , vital:26576
- Description: The Scotsman Seabream, Polysteganus praeorbitalis, is one of several large, slow-growing members of the Sparidae family of fishes endemic to the Agulhas Current system in the Western Indian Ocean (WIO). Relatively little research has been conducted on this species despite its importance to both recreational and commercial line fisheries in South Africa and the drastic decline in catch per unit effort (CPUE) that has been recorded since the 1940s. Changing sea temperatures as a result of global climate change are further expected to affect the distribution and abundance of many fish species based on their thermal tolerances, life histories and population structures. The ability of these species to shift their distribution and adapt to new environments and thermal conditions will depend to some degree on the levels of genetic variation and gene flow, within and between populations. A combined approach using species distribution modelling and genetic analyses may prove to be a useful tool in investigating the potential effects of climate change on the distribution and genetic diversity of species. An ensemble species distribution model (SDM) based on 205 occurrence records and 30 years of Reynolds Optimum Interpolated (OI) sea surface temperature data was constructed to predict the distributional response of P. praeorbitalis to climate change in the Agulhas Current system. The ensemble SDM displayed a true skill statistic (TSS) of 0.975 and an area under the receiver operating curve (ROC) of 0.999, indicating good model fit. Autumn and winter minimum temperatures, as well as bathymetry, were the most important predictor variables in the majority of models, indicating that these variables may directly constrain the distribution of P. praeorbitalis. In particular, the southern range edge of this species appeared to be constrained by autumn and winter minima, with high model agreement on this range edge. Conversely, the northern range limit showed poor model agreement leading to a gradual reduction in occurrence. This indicates that this range edge may be constrained by other factors not included in the models such as species interactions. The ensemble SDM projected the current range of P. praeorbitalis to be 1500 km², smaller than the published range for this species. The model underestimated the northern range edge of this species by approximately 5° latitude when binary transformed. This is probably due to the rarity of this species in the landings of the Mozambican linefishery, which was assumed to be an indication of low abundance of P. praeorbitalis in these waters. The absence of a specimen to verify the published northern range edge of this species indicates that the northern range edge produced by this model is likely to be closer to the actual range limit of the species. A range contraction of 30% occurring at both the northern and southern edge of P. praeorbitalis’ range and range fragmentation occurring, towards its northern range edge by 2030, was predicted. These changes are modelled to be the results of cooling related to the intensification of the Port Alfred upwelling cell and of warming predicted north of the Natal Bight and in southern Mozambique. Genetic analyses of the nuclear DNA (nDNA) S7 intron 1 and mitochondrial DNA (mtDNA) control region genes were carried out using 118 tissue samples of P. praeorbitalis collected at four main localities: the Eastern Cape, Transkei, southern KwaZulu-Natal and northern KwaZulu-Natal. Analyses of genetic diversity levels revealed relatively low diversity in the mtDNA dataset (Hd = 0.488; π = 0.004) and moderate levels of diversity in the nDNA dataset (Ad = 0.922; π = 0.005). The low levels of diversity observed in the mtDNA dataset might be explained by a number of factors, including high variation in spawning success, the negative effects of over-harvesting, or a recent population bottleneck. The last explanation is supported by characteristic star-shaped haplotype networks and unimodal mismatch distributions displayed by both datasets. These results, in conjunction with a significant (p = 0.005) negative Tajimas D value (-2.029) in the mtDNA dataset and significant (p = 0.0005) negative Fu’s F statistic in both the nDNA (F = -26.5) and mtDNA (F = -11.9) datasets, provide strong evidence for a recent population expansion after a bottleneck event in this species. Spatially, mtDNA diversity was highest in the Eastern Cape and lowest in the middle localities, while nDNA diversity showed the opposite pattern. These results may be indicative of differences in the sex ratio between localities, possibly as a result of the protogynous hermaphroditism that has been postulated for this species. Although pairwise comparisons and exact tests of population differentiation revealed no significant geneticdifferentiation between populations in the mtDNA dataset, there was some evidence of low levels of differentiation in the nDNA dataset. This occurred for comparisons between the Eastern Cape and Transkei (Fst = 0.039; p <0.05), and the northern KwaZulu-Natal (Fst = 0.045; p < 0.05).. This might be the result of one or a combination of factors including the effects of the Port Alfred upwelling cell on dispersal and gene flow, or the possibility of more than one spawning ground for this species promoting sub-structuring. A SAMOVA analyses run on the nDNA dataset maximised variance by grouping the Eastern Cape and southern KwaZulu-Natal together and Transkei and northern KwaZulu-Natal together in two groups. This revealed no evidence of spatial structure (p = 0.36), with only 3.30% of variation explained by this grouping. The removal of individuals below the estimated length at 50% maturity in the nDNA dataset, in order to test for temporal structure, resulted in stronger evidence of differentiation between the Eastern Cape and all other localities: Transkei (Fst = 0.081; p< 0.05), southern KwaZulu-Natal (Fst = 0.031; p<0.05), and northern KwaZulu-Natal (Fst = 0.078; p< 0.05). This indicates that some temporal genetic structure may exist between age classes within this species. The differentiation observed between the Eastern Cape and other localities, coupled with the high percentage of private haplotypes in the mtDNA dataset in this locality, indicates that this area is where P. praeorbitalis is most vulnerable to the potential negative effects of climate change on its genetic diversity. However, the vast majority of this species genetic diversity appears to reside towards the centre of its range where it is most abundant and the lack of strong genetic structure indicates high levels of gene flow. In conclusion, while P. praeorbitalis is vulnerable to range loss as a result of climate change, its genetic diversity is unlikely to be greatly affected.
- Full Text:
- Date Issued: 2014
- Authors: Isemonger, Devin Neil
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54509 , vital:26576
- Description: The Scotsman Seabream, Polysteganus praeorbitalis, is one of several large, slow-growing members of the Sparidae family of fishes endemic to the Agulhas Current system in the Western Indian Ocean (WIO). Relatively little research has been conducted on this species despite its importance to both recreational and commercial line fisheries in South Africa and the drastic decline in catch per unit effort (CPUE) that has been recorded since the 1940s. Changing sea temperatures as a result of global climate change are further expected to affect the distribution and abundance of many fish species based on their thermal tolerances, life histories and population structures. The ability of these species to shift their distribution and adapt to new environments and thermal conditions will depend to some degree on the levels of genetic variation and gene flow, within and between populations. A combined approach using species distribution modelling and genetic analyses may prove to be a useful tool in investigating the potential effects of climate change on the distribution and genetic diversity of species. An ensemble species distribution model (SDM) based on 205 occurrence records and 30 years of Reynolds Optimum Interpolated (OI) sea surface temperature data was constructed to predict the distributional response of P. praeorbitalis to climate change in the Agulhas Current system. The ensemble SDM displayed a true skill statistic (TSS) of 0.975 and an area under the receiver operating curve (ROC) of 0.999, indicating good model fit. Autumn and winter minimum temperatures, as well as bathymetry, were the most important predictor variables in the majority of models, indicating that these variables may directly constrain the distribution of P. praeorbitalis. In particular, the southern range edge of this species appeared to be constrained by autumn and winter minima, with high model agreement on this range edge. Conversely, the northern range limit showed poor model agreement leading to a gradual reduction in occurrence. This indicates that this range edge may be constrained by other factors not included in the models such as species interactions. The ensemble SDM projected the current range of P. praeorbitalis to be 1500 km², smaller than the published range for this species. The model underestimated the northern range edge of this species by approximately 5° latitude when binary transformed. This is probably due to the rarity of this species in the landings of the Mozambican linefishery, which was assumed to be an indication of low abundance of P. praeorbitalis in these waters. The absence of a specimen to verify the published northern range edge of this species indicates that the northern range edge produced by this model is likely to be closer to the actual range limit of the species. A range contraction of 30% occurring at both the northern and southern edge of P. praeorbitalis’ range and range fragmentation occurring, towards its northern range edge by 2030, was predicted. These changes are modelled to be the results of cooling related to the intensification of the Port Alfred upwelling cell and of warming predicted north of the Natal Bight and in southern Mozambique. Genetic analyses of the nuclear DNA (nDNA) S7 intron 1 and mitochondrial DNA (mtDNA) control region genes were carried out using 118 tissue samples of P. praeorbitalis collected at four main localities: the Eastern Cape, Transkei, southern KwaZulu-Natal and northern KwaZulu-Natal. Analyses of genetic diversity levels revealed relatively low diversity in the mtDNA dataset (Hd = 0.488; π = 0.004) and moderate levels of diversity in the nDNA dataset (Ad = 0.922; π = 0.005). The low levels of diversity observed in the mtDNA dataset might be explained by a number of factors, including high variation in spawning success, the negative effects of over-harvesting, or a recent population bottleneck. The last explanation is supported by characteristic star-shaped haplotype networks and unimodal mismatch distributions displayed by both datasets. These results, in conjunction with a significant (p = 0.005) negative Tajimas D value (-2.029) in the mtDNA dataset and significant (p = 0.0005) negative Fu’s F statistic in both the nDNA (F = -26.5) and mtDNA (F = -11.9) datasets, provide strong evidence for a recent population expansion after a bottleneck event in this species. Spatially, mtDNA diversity was highest in the Eastern Cape and lowest in the middle localities, while nDNA diversity showed the opposite pattern. These results may be indicative of differences in the sex ratio between localities, possibly as a result of the protogynous hermaphroditism that has been postulated for this species. Although pairwise comparisons and exact tests of population differentiation revealed no significant geneticdifferentiation between populations in the mtDNA dataset, there was some evidence of low levels of differentiation in the nDNA dataset. This occurred for comparisons between the Eastern Cape and Transkei (Fst = 0.039; p <0.05), and the northern KwaZulu-Natal (Fst = 0.045; p < 0.05).. This might be the result of one or a combination of factors including the effects of the Port Alfred upwelling cell on dispersal and gene flow, or the possibility of more than one spawning ground for this species promoting sub-structuring. A SAMOVA analyses run on the nDNA dataset maximised variance by grouping the Eastern Cape and southern KwaZulu-Natal together and Transkei and northern KwaZulu-Natal together in two groups. This revealed no evidence of spatial structure (p = 0.36), with only 3.30% of variation explained by this grouping. The removal of individuals below the estimated length at 50% maturity in the nDNA dataset, in order to test for temporal structure, resulted in stronger evidence of differentiation between the Eastern Cape and all other localities: Transkei (Fst = 0.081; p< 0.05), southern KwaZulu-Natal (Fst = 0.031; p<0.05), and northern KwaZulu-Natal (Fst = 0.078; p< 0.05). This indicates that some temporal genetic structure may exist between age classes within this species. The differentiation observed between the Eastern Cape and other localities, coupled with the high percentage of private haplotypes in the mtDNA dataset in this locality, indicates that this area is where P. praeorbitalis is most vulnerable to the potential negative effects of climate change on its genetic diversity. However, the vast majority of this species genetic diversity appears to reside towards the centre of its range where it is most abundant and the lack of strong genetic structure indicates high levels of gene flow. In conclusion, while P. praeorbitalis is vulnerable to range loss as a result of climate change, its genetic diversity is unlikely to be greatly affected.
- Full Text:
- Date Issued: 2014
Prioritising native fish populations for conservation using genetics in the Groot Marico catchment, North West Province, South Africa
- Authors: Van der Walt, Kerry-Ann
- Date: 2014
- Subjects: Native fishes Fishery management -- South Africa -- North West Fish populations Fishes -- Conservation -- South Africa -- Western Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/69102 , vital:29390
- Description: The Groot Marico catchment in the North West Province is a National Freshwater Ecosystem Priority Area (NFEPA) because it represents unique landscape features with unique biodiversity that are considered to be of special ecological significance. Three native freshwater species Amphilius uranoscopus, Chiloglanis pretoriae and Barbus motebensis, have high local conservation importance and B. motebensis is endemic to the catchment and is IUCN-listed as vulnerable. The main objective of this study is to contribute towards the effective conservation of these three species in the Groot Marico River system by assessing their genetic structure to determine whether tributary populations of the three species comprise of one genetic population or whether they are divided into genetically distinct subpopulations, in order to prioritise areas for conservation. The central null hypothesis was that there is no genetic differentiation between tributary populations (i.e., panmixia) of B. motebensis, A. uranoscopus and C. pretoriae in the Groot Marico catchment, North West Province. In total, 80 individuals per species were collected, targeting at least 10 individuals per population from a total of eight populations (seven tributaries and the Groot Marico main stem) and across the study area. Samples were collected by electrofishing and specimens were euthanized using an overdose of clove oil. A sample of muscle tissue was removed for genetic evaluation and the remainder of the specimens served as voucher specimens. For the genetic evaluation, mitochondrial (ND2, cyt b) and nuclear (S7) genes were used. Genetic techniques used were DNA extraction, polymerase chain reaction (PCR), purification and sequencing. From the 240 individuals collected, 123 sequences for B. motebensis, 111 sequences for A. uranoscopus and 103 sequences for C. pretoriae were analysed across all three genes. Statistical analysis included looking at cleaned sequences in order to obtain models using MODELTEST (version 3.06). Population structuring and phylogeographic analysis was performed in Arlequin (version 2000), TCS (version 1.2.1) and PAUP*. Results indicated that for B. motebensis the null hypothesis could be rejected as there were two distinct lineages (the Draai and Eastern lineages) that demonstrated significant divergence in both the ND2 and S7 genes, suggesting historical isolation. The low divergence in the mitochondrial cytochrome b gene (0% < D < 0.8%) suggests that this isolation is not very old and is probably not comparable to species level differentiation. The null hypothesis was also rejected for A. uranoscopus as there were also significant levels of differentiation between tributary populations resulting in the identification of two lineages (the Ribbok and Western lineages). However, for C. pretoriae, the null hypothesis could not be rejected as there was no genetic differentiation between tributary populations i.e., one panmictic population. Therefore, due to each species showing different genetic structuring within the tributary populations, more than one priority area for conservation needs to be implemented. These priority areas of conservation where therefore evaluated based on the current conservation status of the species (B. motebensis being vulnerable on the IUCN Red List), the number of Evolutionary Significant Units for each species and the overall genetic diversity of all three species in the Groot Marico catchment. In total, four tributary populations were conservation priorities areas, these were the Draai, Vanstraatens, Ribbok and Kaaloog tributaries. The Draai, Vanstraatens and Kaaloog tributaries were selected as priority areas for B. motebensis (B. motebensis is considered to be the most vulnerable of all three species). The Draai tributary was selected due to the B. motebensis population within the tributary showing isolation from the rest of the tributary populations. In order to conserve B. motebensis from the Southern lineage, the Vanstraatens and Kaaloog tributaries were selected. Reasons for selecting these two specific tributaries within the Southern lineage were that the Vanstraatens tributary had unique alleles (three Evolutionary Significant Units) for B. motebensis and the Kaaloog tributary had high genetic diversity (HD = 0.889, ND2 gene) when compared to the other tributary populations. The Ribbok and Vanstraatens tributaries were selected as priority areas for the conservation of A. uranoscopus. The Ribbok tributary was selected as it showed isolation from the rest of the tributary populations, as seen with the Draai tributary (B. motebensis) and the Vanstraatens tributary was selected to represent the Western lineage as it had the highest diversity for both genes (ND2 and S7). The Ribbok tributary has the highest prioritisation when compared to the Vanstraatens tributary. Chiloglanis pretoriae occurs within the Draai, Vanstraatens, Ribbok and Kaaloog tributaries, therefore by prioritising these tributaries for conservation, C. pretoriae will in turn be conserved.
- Full Text:
- Date Issued: 2014
- Authors: Van der Walt, Kerry-Ann
- Date: 2014
- Subjects: Native fishes Fishery management -- South Africa -- North West Fish populations Fishes -- Conservation -- South Africa -- Western Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/69102 , vital:29390
- Description: The Groot Marico catchment in the North West Province is a National Freshwater Ecosystem Priority Area (NFEPA) because it represents unique landscape features with unique biodiversity that are considered to be of special ecological significance. Three native freshwater species Amphilius uranoscopus, Chiloglanis pretoriae and Barbus motebensis, have high local conservation importance and B. motebensis is endemic to the catchment and is IUCN-listed as vulnerable. The main objective of this study is to contribute towards the effective conservation of these three species in the Groot Marico River system by assessing their genetic structure to determine whether tributary populations of the three species comprise of one genetic population or whether they are divided into genetically distinct subpopulations, in order to prioritise areas for conservation. The central null hypothesis was that there is no genetic differentiation between tributary populations (i.e., panmixia) of B. motebensis, A. uranoscopus and C. pretoriae in the Groot Marico catchment, North West Province. In total, 80 individuals per species were collected, targeting at least 10 individuals per population from a total of eight populations (seven tributaries and the Groot Marico main stem) and across the study area. Samples were collected by electrofishing and specimens were euthanized using an overdose of clove oil. A sample of muscle tissue was removed for genetic evaluation and the remainder of the specimens served as voucher specimens. For the genetic evaluation, mitochondrial (ND2, cyt b) and nuclear (S7) genes were used. Genetic techniques used were DNA extraction, polymerase chain reaction (PCR), purification and sequencing. From the 240 individuals collected, 123 sequences for B. motebensis, 111 sequences for A. uranoscopus and 103 sequences for C. pretoriae were analysed across all three genes. Statistical analysis included looking at cleaned sequences in order to obtain models using MODELTEST (version 3.06). Population structuring and phylogeographic analysis was performed in Arlequin (version 2000), TCS (version 1.2.1) and PAUP*. Results indicated that for B. motebensis the null hypothesis could be rejected as there were two distinct lineages (the Draai and Eastern lineages) that demonstrated significant divergence in both the ND2 and S7 genes, suggesting historical isolation. The low divergence in the mitochondrial cytochrome b gene (0% < D < 0.8%) suggests that this isolation is not very old and is probably not comparable to species level differentiation. The null hypothesis was also rejected for A. uranoscopus as there were also significant levels of differentiation between tributary populations resulting in the identification of two lineages (the Ribbok and Western lineages). However, for C. pretoriae, the null hypothesis could not be rejected as there was no genetic differentiation between tributary populations i.e., one panmictic population. Therefore, due to each species showing different genetic structuring within the tributary populations, more than one priority area for conservation needs to be implemented. These priority areas of conservation where therefore evaluated based on the current conservation status of the species (B. motebensis being vulnerable on the IUCN Red List), the number of Evolutionary Significant Units for each species and the overall genetic diversity of all three species in the Groot Marico catchment. In total, four tributary populations were conservation priorities areas, these were the Draai, Vanstraatens, Ribbok and Kaaloog tributaries. The Draai, Vanstraatens and Kaaloog tributaries were selected as priority areas for B. motebensis (B. motebensis is considered to be the most vulnerable of all three species). The Draai tributary was selected due to the B. motebensis population within the tributary showing isolation from the rest of the tributary populations. In order to conserve B. motebensis from the Southern lineage, the Vanstraatens and Kaaloog tributaries were selected. Reasons for selecting these two specific tributaries within the Southern lineage were that the Vanstraatens tributary had unique alleles (three Evolutionary Significant Units) for B. motebensis and the Kaaloog tributary had high genetic diversity (HD = 0.889, ND2 gene) when compared to the other tributary populations. The Ribbok and Vanstraatens tributaries were selected as priority areas for the conservation of A. uranoscopus. The Ribbok tributary was selected as it showed isolation from the rest of the tributary populations, as seen with the Draai tributary (B. motebensis) and the Vanstraatens tributary was selected to represent the Western lineage as it had the highest diversity for both genes (ND2 and S7). The Ribbok tributary has the highest prioritisation when compared to the Vanstraatens tributary. Chiloglanis pretoriae occurs within the Draai, Vanstraatens, Ribbok and Kaaloog tributaries, therefore by prioritising these tributaries for conservation, C. pretoriae will in turn be conserved.
- Full Text:
- Date Issued: 2014
Synthesis and characterization of NaYGdF4 upconversion nanoparticles and an investigation of their effects on the spectroscopic properties of two phthalocyanine dyes
- Authors: Taylor, Jessica Mary
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54621 , vital:26594
- Description: Sphere and star shaped NaYGdF4:Yb/Er(Tm) upconversion nanoparticles were successfully synthesized utilizing a methanol assisted thermal decomposition approach and their chemical, spectroscopic and fluorescence properties were fully characterized. In addition, their influence on the spectroscopic and fluorescence properties of two phthalocyanines (Pcs) (unsubstituted tetrathiophenoxy phthalocyanine (H2Pc) and aluminium octacarboxy phthalocyanine (Cl)AlOCPc) was investigated. Upconversion nanoparticles were found to produce characteristic upconversion fluorescence emissions in the blue, green, red and NIR regions and were also shown to possess paramagnetic properties. Simple mixing with an H2Pc in toluene was found to exert no change on the spectroscopic or fluorescence properties of the Pc while covalent conjugation to a (Cl)AlOCPc resulted in a large Q band blue shift accompanied by a decrease in fluorescence lifetimes in DMSO. The red light excitation mediated singlet oxygen generation of the H2Pc mixed with upconversion nanoparticles was investigated and singlet oxygen fluorescence lifetimes were found to decrease in the presence of the nanoparticles. Upconversion mediated singlet oxygen generation, by way of resonance energy transfer to the Pc, was also attempted using 972 nm excitation; however, no singlet oxygen was detected utilizing singlet oxygen NIR emission detection. Pending further work using alternative singlet oxygen detection methods, this suggests that while upconversion nanoparticles possess excellent fluorescent imaging capabilities, they are relatively inefficient in inducing singlet oxygen production simply when mixed with phthalocyanines. Despite this, by combining phthalocyanines and upconversion nanoparticles, we present a system capable of: multimodal imaging, using both upconversion and phthalocyanines emissions, singlet oxygen generation, via direct excitation of the phthalocyanine with red laser light, and, possibly, magnetic resonance imaging, as a result of doping the upconversion nanoparticles with Gd3+ ions.
- Full Text:
- Date Issued: 2014
- Authors: Taylor, Jessica Mary
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54621 , vital:26594
- Description: Sphere and star shaped NaYGdF4:Yb/Er(Tm) upconversion nanoparticles were successfully synthesized utilizing a methanol assisted thermal decomposition approach and their chemical, spectroscopic and fluorescence properties were fully characterized. In addition, their influence on the spectroscopic and fluorescence properties of two phthalocyanines (Pcs) (unsubstituted tetrathiophenoxy phthalocyanine (H2Pc) and aluminium octacarboxy phthalocyanine (Cl)AlOCPc) was investigated. Upconversion nanoparticles were found to produce characteristic upconversion fluorescence emissions in the blue, green, red and NIR regions and were also shown to possess paramagnetic properties. Simple mixing with an H2Pc in toluene was found to exert no change on the spectroscopic or fluorescence properties of the Pc while covalent conjugation to a (Cl)AlOCPc resulted in a large Q band blue shift accompanied by a decrease in fluorescence lifetimes in DMSO. The red light excitation mediated singlet oxygen generation of the H2Pc mixed with upconversion nanoparticles was investigated and singlet oxygen fluorescence lifetimes were found to decrease in the presence of the nanoparticles. Upconversion mediated singlet oxygen generation, by way of resonance energy transfer to the Pc, was also attempted using 972 nm excitation; however, no singlet oxygen was detected utilizing singlet oxygen NIR emission detection. Pending further work using alternative singlet oxygen detection methods, this suggests that while upconversion nanoparticles possess excellent fluorescent imaging capabilities, they are relatively inefficient in inducing singlet oxygen production simply when mixed with phthalocyanines. Despite this, by combining phthalocyanines and upconversion nanoparticles, we present a system capable of: multimodal imaging, using both upconversion and phthalocyanines emissions, singlet oxygen generation, via direct excitation of the phthalocyanine with red laser light, and, possibly, magnetic resonance imaging, as a result of doping the upconversion nanoparticles with Gd3+ ions.
- Full Text:
- Date Issued: 2014
The involvement of TRAP1 in the mitochondrial localization of STAT3 in mammalian cells
- Authors: Kadye, Rose
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/55760 , vital:26731
- Description: STAT3 (signal transducer and activator of transcription 3), an oncogene and transcription factor of genes involved in cellular differentiation, proliferation and immune function, that classically localizes in the cytosol and nucleus has also been found in the mitochondria. However, STAT3 does not have a mitochondrial transit peptide, and its mechanism for mitochondrial localization is unknown. Cytosolic Hsp90s chaperone STAT3 to the nucleus therefore we investigated the involvement of the nuclear-encoded mitochondrial Hsp90 molecular chaperone tumor necrosis receptor associated protein 1 (TRAP1) in STAT3’s mitochondrial localization. Using TRAP1 transient over-expression, STAT3 inhibitor S3I- 201 and Hsp90 inhibitor geldanamycin, we demonstrate that TRAP1 and STAT3 co-localize and co-immunoprecipitates in mammalian systems. Taken together with the observation that STAT3 potentially directly interacts with TRAP1, these data suggest that TRAP1 plays a role in the mitochondrial localization of STAT3.
- Full Text:
- Date Issued: 2014
- Authors: Kadye, Rose
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/55760 , vital:26731
- Description: STAT3 (signal transducer and activator of transcription 3), an oncogene and transcription factor of genes involved in cellular differentiation, proliferation and immune function, that classically localizes in the cytosol and nucleus has also been found in the mitochondria. However, STAT3 does not have a mitochondrial transit peptide, and its mechanism for mitochondrial localization is unknown. Cytosolic Hsp90s chaperone STAT3 to the nucleus therefore we investigated the involvement of the nuclear-encoded mitochondrial Hsp90 molecular chaperone tumor necrosis receptor associated protein 1 (TRAP1) in STAT3’s mitochondrial localization. Using TRAP1 transient over-expression, STAT3 inhibitor S3I- 201 and Hsp90 inhibitor geldanamycin, we demonstrate that TRAP1 and STAT3 co-localize and co-immunoprecipitates in mammalian systems. Taken together with the observation that STAT3 potentially directly interacts with TRAP1, these data suggest that TRAP1 plays a role in the mitochondrial localization of STAT3.
- Full Text:
- Date Issued: 2014
A study of four-dimensional oscillator groups and the associated left-invariant control affine systems
- Authors: Biggs, Rory
- Date: 2012
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164941 , vital:41186
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Department of Mathematics, 2012
- Full Text:
- Date Issued: 2012
- Authors: Biggs, Rory
- Date: 2012
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164941 , vital:41186
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Department of Mathematics, 2012
- Full Text:
- Date Issued: 2012
Human-river relationships in the Kat River catchment and the implications for integrated water resource management (IWRM) : an exploraratory study
- Authors: Birkholz, Sharon Alice
- Date: 2009
- Subjects: Aquatic ecology -- South Africa -- Kat River , Rivers -- South Africa -- Kat River -- Sociological aspects , Rivers -- South Africa -- Kat River , Water supply -- South Africa -- Kat River -- Management , Human ecology -- South Africa -- Kat River , Stream ecology -- South Africa -- Kat River
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:4838 , http://hdl.handle.net/10962/d1005514
- Description: Through out this study ‘relational scenarios’ were seen as the possible outcomes of the expression of human-river relationships in a catchment. Working within Inglis’s (2008, pg. 10) comment that ‘the Human World Relationship is expressed through a person’s views and behaviour towards the natural world, which can be either constructive or destructive’, two relational scenarios were selected to represent these two predicted outcomes of human-environment (or in the case of this thesis human-river) relationships: IWRM, seen as constructive and mutually beneficial to both the social and ecological system, and the Tragedy of the Commons, seen as destructive and parasitic in nature. In respect to this assertion, a conceptual framework or model was developed and used to guide the inductive process of this research. Through a social survey (administered via semi-structured interviews) of stakeholders (water-users) in the Kat River Catchment, Eastern Cape, South Africa, social attitudes towards the Kat River were explored. These attitudes were considered as variables that relate to the expression of ‘Human World Relationships’ namely ‘values and behaviour’ (Inglis, 2008, pg. 10). The findings of this thesis confirm that attitudes are influential components of human-river relationships in the Kat River Catchment. It was observed from the findings that the attitudes individuals have towards the Kat River have the potential to influence the ways people interact with the River and its associated resources, and are in turn influenced by the condition of the River and connections people have or make with the River within their daily lives. Such relationships in turn affect the management of the River and its water resources and influence how individuals approach water-related issues and undertake the associated activities. Given this understanding it was then proposed that attitudes could provide information that enables the prediction of likely ‘relational scenarios’ (IWRM or the Tragedy of the Commons) in a catchment. The findings appear to support this proposal, and three main attitude groups (utilitarian, associative and dissociative) were identified and used to further the discussion into how this knowledge could be used in predicting possible relational scenarios based on human-river relationships. Further exploration of the identified attitude groups suggested that these variables are significantly influenced by environmental ethics and place attachment (present in the community) and a series of guiding frameworks were developed to facilitate the exploration of the attitude groups relative to these concepts. The frameworks were generated from the hypothesis that knowledge of attitude groups in a catchment, in connection with the relative degrees to which moral values and worldviews are expressed, could provide insight into the readiness of a catchment system for the implementation of IWRM and/or the facilitative steps needed to shift the influence of unfavourable attitude groups (i.e. dissociative attitudes). Such steps would most likely involve extensive educational, awareness and capacity building programs. Finally, given the above theoretical frameworks, inductively developed from the findings of the social survey and related literature, the conceptual model was reevaluated and extended to include the thesis findings and hypotheses. It is suggested that in a catchment where there is a balance between the expression of utilitarian and associative attitude groups, then there is a high probability of finding present evidence of mutually beneficial human-river relationships already in play, as well as ‘fertile soil’ for the promotion of IWRM and philosophies and skills that generate such relationships. Alternatively in an area with a strong expression of dissociative attitudes, it is more likely to find evidence of destructive, more parasitic-like relationships being expressed, and a lack of commitment and interest in being involved in changing the status quo. It is likely that where both associative and dissociative attitudes are present there will be an overlap of elements of both scenarios – a situation that is probable in most catchments – depending on the strength of expression of either attitude group the balance will shift (be shifting) between the two relational scenarios.
- Full Text:
- Date Issued: 2009
- Authors: Birkholz, Sharon Alice
- Date: 2009
- Subjects: Aquatic ecology -- South Africa -- Kat River , Rivers -- South Africa -- Kat River -- Sociological aspects , Rivers -- South Africa -- Kat River , Water supply -- South Africa -- Kat River -- Management , Human ecology -- South Africa -- Kat River , Stream ecology -- South Africa -- Kat River
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:4838 , http://hdl.handle.net/10962/d1005514
- Description: Through out this study ‘relational scenarios’ were seen as the possible outcomes of the expression of human-river relationships in a catchment. Working within Inglis’s (2008, pg. 10) comment that ‘the Human World Relationship is expressed through a person’s views and behaviour towards the natural world, which can be either constructive or destructive’, two relational scenarios were selected to represent these two predicted outcomes of human-environment (or in the case of this thesis human-river) relationships: IWRM, seen as constructive and mutually beneficial to both the social and ecological system, and the Tragedy of the Commons, seen as destructive and parasitic in nature. In respect to this assertion, a conceptual framework or model was developed and used to guide the inductive process of this research. Through a social survey (administered via semi-structured interviews) of stakeholders (water-users) in the Kat River Catchment, Eastern Cape, South Africa, social attitudes towards the Kat River were explored. These attitudes were considered as variables that relate to the expression of ‘Human World Relationships’ namely ‘values and behaviour’ (Inglis, 2008, pg. 10). The findings of this thesis confirm that attitudes are influential components of human-river relationships in the Kat River Catchment. It was observed from the findings that the attitudes individuals have towards the Kat River have the potential to influence the ways people interact with the River and its associated resources, and are in turn influenced by the condition of the River and connections people have or make with the River within their daily lives. Such relationships in turn affect the management of the River and its water resources and influence how individuals approach water-related issues and undertake the associated activities. Given this understanding it was then proposed that attitudes could provide information that enables the prediction of likely ‘relational scenarios’ (IWRM or the Tragedy of the Commons) in a catchment. The findings appear to support this proposal, and three main attitude groups (utilitarian, associative and dissociative) were identified and used to further the discussion into how this knowledge could be used in predicting possible relational scenarios based on human-river relationships. Further exploration of the identified attitude groups suggested that these variables are significantly influenced by environmental ethics and place attachment (present in the community) and a series of guiding frameworks were developed to facilitate the exploration of the attitude groups relative to these concepts. The frameworks were generated from the hypothesis that knowledge of attitude groups in a catchment, in connection with the relative degrees to which moral values and worldviews are expressed, could provide insight into the readiness of a catchment system for the implementation of IWRM and/or the facilitative steps needed to shift the influence of unfavourable attitude groups (i.e. dissociative attitudes). Such steps would most likely involve extensive educational, awareness and capacity building programs. Finally, given the above theoretical frameworks, inductively developed from the findings of the social survey and related literature, the conceptual model was reevaluated and extended to include the thesis findings and hypotheses. It is suggested that in a catchment where there is a balance between the expression of utilitarian and associative attitude groups, then there is a high probability of finding present evidence of mutually beneficial human-river relationships already in play, as well as ‘fertile soil’ for the promotion of IWRM and philosophies and skills that generate such relationships. Alternatively in an area with a strong expression of dissociative attitudes, it is more likely to find evidence of destructive, more parasitic-like relationships being expressed, and a lack of commitment and interest in being involved in changing the status quo. It is likely that where both associative and dissociative attitudes are present there will be an overlap of elements of both scenarios – a situation that is probable in most catchments – depending on the strength of expression of either attitude group the balance will shift (be shifting) between the two relational scenarios.
- Full Text:
- Date Issued: 2009
Environmental and socio-economic effects associated with the planting of Atriplex nummularia Lindl. (Oldman saltbush) in the Karoo
- Authors: Hobson, Colin Desmond
- Date: 1991
- Subjects: Botany, Economic Plant introduction -- South Africa -- Karoo Plants, Cultivated
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:4794 , http://hdl.handle.net/10962/d1001894
- Description: This study examines the environmental and socio-economic effects associated with the planting of Atriplex nummularia Lindl. (Oldman saltbush) in the karoo. This is the first study of its kind on oldman saltbush and serves as an important scoping exercise in assessing the impact of saltbush on its surrounds and in identifying additional aspects which require investigation. The environmental parameters investigated include microclimatic effects, soil induced changes, salinity effects on the germination of selected karoo species and compositional changes in the indigenous plant community within a saltbush plantation. When compared to indigenous karoo plant species oldman saltbush is found to ameliorate soil temperatures and increase surface soil salinity (specifically sodium chloride), on an individual plant basis. Salinity is shown to have a differential effect on the germination of selected karoo shrubs. The indigenous plant community within a forty year old saltbush plantation is impoverished with both density of individuals and species richness being markedly reduced. Saltbush is identified as an unsuitable nurse plant for the majority of karoo shrubs. Farm size in relation to both actual and intended area established to saltbush is considered. The area of saltbush already established in the karoo is considered too insignificant to have any wide socio-economic impact. Farmers who intend planting large areas of their farms to saltbush are in the minority. It is those farmers who already have some saltbush planted, who intend planting more. Ecologically based management guidelines are presented, suggesting practices which minimize the detrimental effects of saltbush on soil salinity and the indigenous plant community. These guidelines are practical and in keeping with the overall objectives of optimum resource utilisation and the national grazing strategy for South Africa.
- Full Text:
- Date Issued: 1991
- Authors: Hobson, Colin Desmond
- Date: 1991
- Subjects: Botany, Economic Plant introduction -- South Africa -- Karoo Plants, Cultivated
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:4794 , http://hdl.handle.net/10962/d1001894
- Description: This study examines the environmental and socio-economic effects associated with the planting of Atriplex nummularia Lindl. (Oldman saltbush) in the karoo. This is the first study of its kind on oldman saltbush and serves as an important scoping exercise in assessing the impact of saltbush on its surrounds and in identifying additional aspects which require investigation. The environmental parameters investigated include microclimatic effects, soil induced changes, salinity effects on the germination of selected karoo species and compositional changes in the indigenous plant community within a saltbush plantation. When compared to indigenous karoo plant species oldman saltbush is found to ameliorate soil temperatures and increase surface soil salinity (specifically sodium chloride), on an individual plant basis. Salinity is shown to have a differential effect on the germination of selected karoo shrubs. The indigenous plant community within a forty year old saltbush plantation is impoverished with both density of individuals and species richness being markedly reduced. Saltbush is identified as an unsuitable nurse plant for the majority of karoo shrubs. Farm size in relation to both actual and intended area established to saltbush is considered. The area of saltbush already established in the karoo is considered too insignificant to have any wide socio-economic impact. Farmers who intend planting large areas of their farms to saltbush are in the minority. It is those farmers who already have some saltbush planted, who intend planting more. Ecologically based management guidelines are presented, suggesting practices which minimize the detrimental effects of saltbush on soil salinity and the indigenous plant community. These guidelines are practical and in keeping with the overall objectives of optimum resource utilisation and the national grazing strategy for South Africa.
- Full Text:
- Date Issued: 1991
Environmental and socio-economic effects associated with the planting of Atriplex nummularia Lindl. (Oldman saltbush) in the Karoo
- Authors: Hobson, Colin Desmond
- Date: 1991
- Subjects: Botany, Economic Plant introduction -- South Africa -- Karoo Plants, Cultivated
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:4175 , http://hdl.handle.net/10962/d1002023
- Description: This study examines the environmental and socio-economic effects associated with the planting of Atriplex nummularia Lindl. (Oldman saltbush) in the karoo. This is the first study of its kind on oldman saltbush and serves as an important scoping exercise in assessing the impact of saltbush on its surrounds and in identifying additional aspects which require investigation. The environmental parameters investigated include microclimatic effects, soil induced changes, salinity effects on the germination of selected karoo species and compositional changes in the indigenous plant community within a saltbush plantation. When compared to indigenous karoo plant species oldman saltbush is found to ameliorate soil temperatures and increase surface soil salinity (specifically sodium chloride), on an individual plant basis. Salinity is shown to have a differential effect on the germination of selected karoo shrubs. The indigenous plant community within a forty year old saltbush plantation is impoverished with both density of individuals and species richness being markedly reduced. Saltbush is identified as an unsuitable nurse plant for the majority of karoo shrubs. Farm size in relation to both actual and intended area established to saltbush is considered. The area of saltbush already established in the karoo is considered too insignificant to have any wide socio-economic impact. Farmers who intend planting large areas of their farms to saltbush are in the minority. It is those farmers who already have some saltbush planted, who intend planting more. Ecologically based management guidelines are presented, suggesting practices which minimize the detrimental effects of saltbush on soil salinity and the indigenous plant community. These guidelines are practical and in keeping with the overall objectives of optimum resource utilisation and the national grazing strategy for South Africa.
- Full Text:
- Date Issued: 1991
- Authors: Hobson, Colin Desmond
- Date: 1991
- Subjects: Botany, Economic Plant introduction -- South Africa -- Karoo Plants, Cultivated
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:4175 , http://hdl.handle.net/10962/d1002023
- Description: This study examines the environmental and socio-economic effects associated with the planting of Atriplex nummularia Lindl. (Oldman saltbush) in the karoo. This is the first study of its kind on oldman saltbush and serves as an important scoping exercise in assessing the impact of saltbush on its surrounds and in identifying additional aspects which require investigation. The environmental parameters investigated include microclimatic effects, soil induced changes, salinity effects on the germination of selected karoo species and compositional changes in the indigenous plant community within a saltbush plantation. When compared to indigenous karoo plant species oldman saltbush is found to ameliorate soil temperatures and increase surface soil salinity (specifically sodium chloride), on an individual plant basis. Salinity is shown to have a differential effect on the germination of selected karoo shrubs. The indigenous plant community within a forty year old saltbush plantation is impoverished with both density of individuals and species richness being markedly reduced. Saltbush is identified as an unsuitable nurse plant for the majority of karoo shrubs. Farm size in relation to both actual and intended area established to saltbush is considered. The area of saltbush already established in the karoo is considered too insignificant to have any wide socio-economic impact. Farmers who intend planting large areas of their farms to saltbush are in the minority. It is those farmers who already have some saltbush planted, who intend planting more. Ecologically based management guidelines are presented, suggesting practices which minimize the detrimental effects of saltbush on soil salinity and the indigenous plant community. These guidelines are practical and in keeping with the overall objectives of optimum resource utilisation and the national grazing strategy for South Africa.
- Full Text:
- Date Issued: 1991
Phenylpropanolamine : analytical and pharmacokinetic studies using high-performance liquid chromatography
- Authors: Scherzinger, Sabine Hilda
- Date: 1988
- Subjects: Phenylpropanolamine , Pharmacokinetics , High performance liquid chromatography
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:3811 , http://hdl.handle.net/10962/d1004528
- Description: Phenylpropanolamine (PPA), a synthetic sympathomimetic amine structurally related to ephedrine has been widely used over t he past 40 years as a nasal decongestant and appetite suppressant. It has been the focus of much controversy concerning the efficacy of the drug in its use as an anorectic agent, and due to the side effects caused by the higher doses of PPA required for appetite suppression. Although extensively used, there is little information concerning the determination of PPA in biological fluids and on the pharmacokinetics of this drug. An adaptation of a published high-performance liquid chromatographic (HPLC) assay for PPA in serum and urine using U.V. detection at 210 nm is presented. PPA was separated in the reversed phase mode. The method has a limit of sensitivity of 5.0 ng/mL and 10.0 ng/mL in serum and urine respectively. Serum concentration data following a single 25 mg dose of phenylpropanolamine in human volunteers demonstrate the application of the analytical method for bioavailability and pharmacokinetic studies. After the administration of 25 mg, 50 mg or 100 mg PPA.HCl solutions to 5 human volunteers, a dose proportionality study demonstrated that PPA appears to exhibit linear kinetics. Linear one body compartment kinetics were assumed and the wagner-Nelson method used to transform in vivo serum data to absorption plots. The serum data were fitted to a model using nonlinear regression techniques to characterize the pharmacokinetic processes of PPA. The absorption of phenylpropanolamine appears to be discontinuous and the drug seems to favour a two body compartment model. The pharmacokinetic parameters obtained from a steady state study using multiple dosing of PPA.HCl solutions compared with those found from previous studies after the administration of sustained-release formulations. A plasma protein binding study using equilibrium dialysis demonstrated that PPA is not highly protein bound in the blood.
- Full Text:
- Date Issued: 1988
- Authors: Scherzinger, Sabine Hilda
- Date: 1988
- Subjects: Phenylpropanolamine , Pharmacokinetics , High performance liquid chromatography
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:3811 , http://hdl.handle.net/10962/d1004528
- Description: Phenylpropanolamine (PPA), a synthetic sympathomimetic amine structurally related to ephedrine has been widely used over t he past 40 years as a nasal decongestant and appetite suppressant. It has been the focus of much controversy concerning the efficacy of the drug in its use as an anorectic agent, and due to the side effects caused by the higher doses of PPA required for appetite suppression. Although extensively used, there is little information concerning the determination of PPA in biological fluids and on the pharmacokinetics of this drug. An adaptation of a published high-performance liquid chromatographic (HPLC) assay for PPA in serum and urine using U.V. detection at 210 nm is presented. PPA was separated in the reversed phase mode. The method has a limit of sensitivity of 5.0 ng/mL and 10.0 ng/mL in serum and urine respectively. Serum concentration data following a single 25 mg dose of phenylpropanolamine in human volunteers demonstrate the application of the analytical method for bioavailability and pharmacokinetic studies. After the administration of 25 mg, 50 mg or 100 mg PPA.HCl solutions to 5 human volunteers, a dose proportionality study demonstrated that PPA appears to exhibit linear kinetics. Linear one body compartment kinetics were assumed and the wagner-Nelson method used to transform in vivo serum data to absorption plots. The serum data were fitted to a model using nonlinear regression techniques to characterize the pharmacokinetic processes of PPA. The absorption of phenylpropanolamine appears to be discontinuous and the drug seems to favour a two body compartment model. The pharmacokinetic parameters obtained from a steady state study using multiple dosing of PPA.HCl solutions compared with those found from previous studies after the administration of sustained-release formulations. A plasma protein binding study using equilibrium dialysis demonstrated that PPA is not highly protein bound in the blood.
- Full Text:
- Date Issued: 1988